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	<h1>Characteristics of Bindings</h1>
	<p>Bindings are assembled from one or more sources, usually called
		their dependencies. A binding observes its dependencies for changes
		and updates its own value according to changes in the dependencies.</p>
	<p>Almost all bindings defined in this library require
		implementations of {@link javafx.beans.Observable} for their
		dependencies. There are two types of implementations already provided,
		the properties in the package {@link javafx.beans.property} and the
		observable collections ({@link javafx.collections.ObservableList} and
		{@link javafx.collections.ObservableMap}). Bindings also implement
		{@code Observable} and can again serve as sources for other bindings
		allowing to construct very complex bindings from simple ones.</p>
	<p>Bindings in our implementation are always calculated lazily.
		That means, if a dependency changes, the result of a binding is not
		immediately recalculated, but it is marked as invalid. Next time the
		value of an invalid binding is requested, it is recalculated.</p>
	<h1>High Level API and Low Level API</h1>
	<p>The Binding API is roughly divided in two parts, the High Level
		Binding API and the Low Level Binding API. The High Level Binding API
		allows to construct simple bindings in an easy to use fashion.
		Defining a binding with the High Level API should be straightforward,
		especially when used in an IDE that provides code completion.
		Unfortunately it has its limitation and at that point the Low Level
		API comes into play. Experienced Java developers can use the Low Level
		API to define bindings, if the functionality of the High Level API is
		not sufficient or to improve the performance. The main goals of the
		Low Level API are fast execution and small memory footprint.</p>
	<p>Following is an example of how both APIs can be used. Assuming
		we have four instances of {@link
		javafx.beans.property.DoubleProperty} {@code a}, {@code b}, {@code
		c} , and {@code d}, we can define a binding that calculates {@code a*b
		+ c*d} with the High Level API for example like this:</p>
	<p>{@code NumberBinding result = Bindings.add (a.multiply(b),
		c.multiply(d)); }</p>
	<p>Defining the same binding using the Low Level API could be done
		like this:</p>
	<pre>
<code>
DoubleBinding foo = new DoubleBinding() {

    {
        super.bind(a, b, c, d);
    }

    &#x40;Override
    protected double computeValue() {
        return a.getValue() * b.getValue() + c.getValue() * d.getValue();
    }
};
</code>
</pre>
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